Hi @markkiu, after testing just now, I was able to set a SIM lock on my own phone (and AGL SIM) without entering an existing PIN.
If yours is asking for one, I think the best thing to do is get in touch with AGL support as the PIN may be specific to your card rather than a default PIN, and if you enter the wrong pin too many times, your device could be locked.
If you have your PUK number, the PIN may be the last 4 digits.
